Hell hath no fury like a 17-year-old with a political cause: If the outcome weren’t so tragic, we might draw that conclusion from Ohio teen Leelah Alcorn’s suicide note.

Born a boy and named Joshua, Alcorn had come to identify as female — and been frustrated by her parents’ response when she came out to them as transgendered. Before walking into traffic on Sunday morning, she left this message on her Tumblr blog:

“The only way I will rest in peace is if one day transgender people aren’t treated the way I was, they’re treated like humans, with valid feelings and human rights.”

There’s more: “Gender needs to be taught about in schools, the earlier the better. My death needs to mean something. My death needs to be counted in the number of transgender people who commit suicide this year. I want someone to look at that number and say ‘that’s f - - ked up’ and fix it. Fix society.”

According to Alcorn, her parents reacted “extremely negatively” when she broke the news. She wrote that her mother told her that it was just a phase and “God doesn’t make mistakes.”

Alcorn’s parents are Christians; they initially banned their son from social-networking sites and decided to homeschool him, in order, they said, to help him get over his inclinations. They sent him to Christian therapists who tried to talk him out of his transgender feelings.

Yet they later relented and let Leelah go back to school and allowed access to social media.

Alcorn’s mother told CNN that her son was on medication for depression and that, while she and her husband didn’t support his choice to be a girl, “We told him that we loved him unconditionally. We loved him no matter what. I loved my son. People need to know that I loved him. He was a good kid, a good boy.”

The Alcorns have suffered a tremendous loss, but sex columnist Dan Savage thinks they have only themselves to blame. He wants them prosecuted for child abuse.

Others agree. A Change.org petition demanding that the headstone say “Leelah,” not “Joshua,” has 55,000 signatures.

The Princeton, NJ-based Transgender Human Rights Institute is pushing Leelah’s Law, a federal ban on “conversion therapy” of all kinds.

This is outrageous. First off, Carla Alcorn wasn’t wrong on the merits: For many transgender kids, it is a just a phase.

As Paul McHugh, the former psychiatrist-in-chief at Johns Hopkins Hospital, recently wrote in The Wall Street Journal, “When children who reported transgender feelings were tracked without medical or surgical treatment at both Vanderbilt University and London’s Portman Clinic, 70 percent-80 percent of them spontaneously lost those feelings.”

McHugh warns against the sex-reassignment surgery that Leelah demanded from her parents for just that reason. (After all, it’s no trivial step — the full course takes years, and key parts are irreversible.)

Second, as McHugh explains, just because you think you were born into the wrong body doesn’t mean that’s actually your medical diagnosis.

We don’t tell anorexics that they’re right about feeling they’re too fat, and need to work to get thinner.

But back to the Alcorns. Are parents now required to embrace everything their teens decide is part of their identity or be accused of child abuse?

Are parents now required to embrace everything their teens decide is part of their identity or be accused of child abuse?

What of all the 16-year-olds who think they’ve found love and want to consummate the relationship as often as possible?

Is this what Savage’s “It Gets Better” movement is really about? It was supposed to inspire young people who were being “bullied” or “harassed” to know that there are people out there who love and support them.

Yet the parental behavior Leelah Alcorn described doesn’t constitute abuse. They just didn’t accept her announcement with open arms.

Perhaps her suicide was a reaction to a recent conversation with her parents. Perhaps it was the result of a lot of emotional issues.

After all, she wrote, “I’m never going to have enough friends to satisfy me. I’m never going to have enough love to satisfy me. I’m never going to find a man who loves me. I’m never going to be happy.”

To judge by her final note, though, Leelah Alcorn saw her suicide as a political act. “Gender needs to be taught in school”; we need to “fix society”; transgender people need “human rights.”

She even wanted her possessions donated to a transgender “civil rights” group.

These are the words of a teen who thinks her own death is going to contribute to a cause.

If you think that finding a “community” online is always going to produce a positive outcome, think again.

Emotionally unstable teens may get some loving notes of support on their Facebook pages, but they may also absorb the rants of activists like Dan Savage.

And those impressionable teens may be inclined to believe that they’re engaged in some kind of larger struggle — one for which they should make the ultimate sacrifice.